Radio wave environment display device and method for displaying radio wave environment

ABSTRACT

A radio wave environment display device includes a display unit that displays a radio wave environment and a controller. The radio wave environment display device displays a radio wave environment in an area where a plurality of wireless transmitters located at different positions transmit radio waves. The controller selects, at each of a plurality of points in the area, a maximum intensity among intensities that are magnitudes of received power of radio waves transmitted from the wireless transmitters and causes the display unit to display the radio wave environment at each of the plurality of points based on the maximum intensity selected and an arrival direction of a radio wave with the maximum intensity selected.

BACKGROUND 1. Technical Field

The present invention relates to a radio wave environment display deviceand a method for displaying a radio wave environment.

2. Description of the Related Art

PTL (Patent Literature) 1 discloses a method in which an area to beestimated is divided into minute sections and reception quality from aplurality of base stations is recognized in each of the minute sections.

Here, PTL 1 is Unexamined Japanese Patent Publication No. 2006-352385.

NPL (Non-Patent Literature) 1 is Tetsuro Imai, “Mobile Radio PropagationSimulation Based on Ray-Tracing Method”, The transactions of theInstitute of Electronics, Information and Communication Engineers B,Vol. J92-B, No. 9, pp. 1333-1347, September 2009.

SUMMARY

The present disclosure provides a radio wave environment display deviceand a method for displaying a radio wave environment that appropriatelydisplays a radio wave environment even if a plurality of wirelesstransmitters transmit different radio waves.

A radio wave environment display device according to one aspect of thepresent disclosure includes a display unit that displays a radio waveenvironment and a controller. The radio wave environment display devicedisplays a radio wave environment in an area where a plurality ofwireless transmitters located at different positions transmit radiowaves. The controller selects, at each of a plurality of points in thearea, a maximum intensity among intensities that are magnitudes ofreceived power of radio waves transmitted from the wireless transmittersand causes the display unit to display the radio wave environment ateach of the plurality of points based on the maximum intensity selectedand an arrival direction of a radio wave with the maximum intensityselected.

A method for displaying a radio wave environment that is performed bythe radio wave environment display device includes selecting, at each ofa plurality of points in the area, a maximum intensity among intensitiesthat are magnitudes of received power of radio waves transmitted from aplurality of wireless transmitters and displaying the radio waveenvironment at each of the plurality of points based on the maximumintensity selected and an arrival direction of a radio wave with themaximum intensity selected.

The radio wave environment display device and the method for displayinga radio wave environment according to the present disclosure enable theradio wave environment to be appropriately displayed even if a pluralityof wireless transmitters transmit different radio waves.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example of a hardwareconfiguration of radio wave environment display device 100 according toan exemplary embodiment.

FIG. 2 is a block diagram illustrating an example of a hardwareconfiguration of radio wave environment display device 100A andperipheral devices according to a modification.

FIG. 3 is a perspective view illustrating a configuration example of amodel area subjected to a simulation by radio wave environment displaydevice 100 illustrated in FIG. 1.

FIG. 4 is a perspective view illustrating a display example of areceived power distribution in the model area subjected to a simulationby radio wave environment display device 100 illustrated in FIG. 1.

FIG. 5 is a perspective view illustrating a display example of acoverage area in the model area subjected to a simulation by radio waveenvironment display device 100 illustrated in FIG. 1.

FIG. 6 is a flowchart of a radio-wave propagation simulation calculationdisplay process performed by radio wave environment display device 100illustrated in FIG. 1.

FIG. 7 is a flowchart of an access-point movement analysis processperformed by radio wave environment display device 100 illustrated inFIG. 1.

FIG. 8 is a flowchart of a person movement analysis process performed byradio wave environment display device 100 illustrated in FIG. 1.

DETAILED DESCRIPTION

Exemplary embodiments will be described in detail below with referenceto the drawings as appropriate. However, in some cases, an unnecessarilydetailed description may be omitted. For example, a detailed descriptionof a well-known matter and a duplicated description of substantially thesame configuration will be omitted in some cases. This is to avoidunnecessary redundancy in the following description and to facilitateunderstanding by those skilled in the art.

It is noted that the accompanying drawings and the description below areprovided to enable those skilled in the art to fully understand thepresent disclosure, and are not intended to limit the subject mattersdescribed in the claims.

First Exemplary Embodiment

FIG. 1 is a block diagram illustrating an example of a hardwareconfiguration of radio wave environment display device 100 according toan exemplary embodiment.

In FIG. 1, radio wave environment display device 100 performs aradio-wave propagation simulation calculation display processillustrated in FIG. 6, an access-point movement analysis processillustrated in FIG. 7, and a person movement analysis processillustrated in FIG. 8 to simulate a radio wave environment based oncalculation basic data 71 of an area model and display a received powerdistribution map and the like. Radio wave environment display device 100includes central processing unit (CPU) 1, and read only memory (ROM) 2,random access memory (RAM) 3, keyboard 4, mouse 5, display 6, and harddisk drive (HDD) 7 that are connected to CPU 1.

CPU 1 configures a controller that controls an entire device. Anoperating system (OS) program is stored in ROM 2. The OS program isexecuted when radio wave environment display device 100 starts up. RAM 3is used as a work region when the radio-wave propagation simulationcalculation display process illustrated in FIG. 6, the access-pointmovement analysis process illustrated in FIG. 7, and the person movementanalysis process illustrated in FIG. 8 are performed. Keyboard 4 andmouse 5, which are operating units, function as a human interface andare used for various settings in the various processes described above.Display 6 not only functions as a human interface but also displayscontents of the various settings, an operating state of the device, anddisplay data 73 of various calculation results and analysis results.Display 6 is an example of display unit.

HDD 7 stores programs 70 for the radio-wave propagation simulationcalculation display process illustrated in FIG. 6, the access-pointmovement analysis process illustrated in FIG. 7, and the person movementanalysis process illustrated in FIG. 8, calculation basic data 71required for calculations in the radio-wave propagation simulationcalculation display process, calculation result data 72, and displaydata 73 that is created based on calculation result data 72. Calculationbasic data 71 includes information about a map of an area, an objectlocated in the area, a material for the object in the area, a positionof a transmitter, and the like.

The program for the radio-wave propagation simulation calculationdisplay process is read from HDD 7 into RAM 3 and then executed.Alternatively, the program may be configured to be recorded in arecording medium other than HDD 7 (for example, compact disk read onlymemory (CD-ROM)) and read from the recording medium into RAM 3 by acompatible reading device (CD-ROM drive device).

FIG. 3 is a perspective view illustrating a configuration example of amodel area subjected to a simulation by radio wave environment displaydevice 100 illustrated in FIG. 1. In the configuration example of themodel area illustrated in FIG. 3, two desks 201, 202 and twelve chairs203 that are radio wave obstacles are arranged in room 200 that isshaped in a rectangle and has a flat bottom surface. Calculation basicdata used in the radio-wave propagation simulation calculation displayprocess includes the following:

(1) Data about transmission power (dBm), frequencies, a modulationmethod, and a gain and height of antennas in wireless transmitters ataccess points AP1, AP2, and the like

(2) Data about a gain and height of an antenna in a wireless receiverassumed and the like

(3) Data about a three-dimensional size of room 200 that is the modelarea

(4) Data about a three-dimensional size and position (two-dimensionalcoordinates in room 200) of a radio wave obstacle

FIG. 4 is a perspective view illustrating a display example of areceived power distribution (S12 in FIG. 6) in a model area subjected toa simulation by radio wave environment display device 100 illustrated inFIG. 1. FIG. 5 is a perspective view illustrating a display example of acoverage area (S22 in FIG. 6) in the model area subjected to asimulation by radio wave environment display device 100 illustrated inFIG. 1. In FIGS. 4 and 5, the received power of radio waves and the likeare represented as a density of black and white hatching because ofrestrictions on online applications. However, the received power isactually represented in colors, for example.

In displaying a radio wave environment in the conventional techniquedisclosed in, for example, PTL 1, received power from two or morewireless transmitters is summed up and resultant received power is thendisplayed. When different radio waves are transmitted from the wirelesstransmitters, radio wave interference occurs in practice. It is thustechnically meaningless to practically display the summed receivedpower. On the other hand, in displaying a radio wave environment asillustrated in FIG. 5, as will be described later in detail, receivedpower of, for example, two radio waves is compared and higher receivedpower is displayed, which is very practical. Other characteristics ofthe exemplary embodiment will be described later in detail.

FIG. 6 is a flowchart of a radio-wave propagation simulation calculationdisplay process performed by radio wave environment display device 100illustrated in FIG. 1. In the present exemplary embodiment, receivedpower of each of points (a plurality of points obtained by dividingmodel area into 100×100, for example) in a model area can be calculatedbased on calculation basic data 71 described above by a well-knownray-tracing method (see NPL 1, for example) or a well-known statisticalestimation method.

At step S1 in FIG. 6, received power of a radio wave from a wirelesstransmitter located at access point AP1 and an arrival direction arecalculated at each point based on calculation basic data 71. At step S2,a calculation result of the received power and the arrival direction arestored in HDD 7 as calculation result data 72, and the process proceedsto step S10. At step S3, received power of a radio wave from a wirelesstransmitter located at access point AP2 and an arrival direction arecalculated at each point based on calculation basic data 71. At step S4,a calculation result of the received power and the arrival direction arestored in HDD 7 as calculation result data 72, and the process proceedsto step S10.

At step S10, a selection display screen for allowing a user to select adisplay of an operation among the following operations is displayed. Asthe user inputs one of menu numbers M1 to M6 through keyboard 4, theprocess branches to step S11 or step S21. When the process proceeds tostep S21, a menu number selected is stored and the process finallyproceeds to one of steps S22, S25, S26, S32, and S42 corresponding tothe menu number selected.

(M1) Received power of radio waves from the wireless transmitters at twoaccess points AP1, AP2 is summed up and a received power distributionmap is then displayed.

(M2) Received power (maximum intensity) of a stronger radio wave ofradio waves from the wireless transmitters at two access points AP1, AP2is selected, the received power of the stronger radio wave selected ismade to correspond to each point in an area, and a coverage area map isdisplayed.

(M3) Received power of a stronger radio wave of radio waves from thewireless transmitters at two access points AP1, AP2 is selected. Inaddition, a difference between the received power of two radio waves iscalculated, a representation of the received power is removed at a pointwith relatively large interference where the difference is less than orequal to a predetermined threshold, and a coverage area map without aninterference area is displayed.

(M4) Received power of a stronger radio wave of radio waves from thewireless transmitters at two access points AP1, AP2 is selected. Inaddition, a difference between the received power of two radio waves iscalculated, and a point with relatively large interference where thedifference is less than or equal to a predetermined threshold isdisplayed as an interference area map.

(M5) Received power of a stronger radio wave of radio waves from thewireless transmitters at two access points AP1, AP2 is selected. Anarrival direction map that illustrates, at each point, a strongestarrival direction among all arrival directions of the received power ofthe stronger radio wave selected is displayed.

(M6) Received power of a stronger radio wave of radio waves from thewireless transmitters at two access points AP1, AP2 is selected. Anarrival direction map is then is displayed. The arrival direction mapillustrates, at each point, a strongest arrival surface direction amongsix surfaces of the received power of the stronger radio wave selected,that is, front, back, left, right, up, and down of the stronger radiowave selected.

When menu number M1 is selected at step S10, at step S11, received powerof radio waves from the wireless transmitters at two access points AP1,AP2 is summed up (S11), the received power distribution map is displayed(S12), and the process returns to step S10.

When menu number M2 is selected at step S10, at step S21, received powerof a stronger radio wave of radio waves from the wireless transmittersat two access points AP1, AP2 is selected, the coverage area map isdisplayed (S22), and the process returns to step S10. It is morepractical to display the coverage area map as compared to a case wherethe received power distribution map that illustrates the received powersummed up is displayed. This is because interference occurs in actualityand thus the received power is not equal to the received power summed upin some cases.

When menu number M3 is selected at step S10, at step S21, received powerof a stronger radio wave of radio waves from the wireless transmittersat two access points AP1, AP2 is selected, and the same time thedifference between the received power of two radio waves is calculated,and a point with relatively large interference where the difference isless than or equal to a predetermined threshold is extracted (S23).Next, a representation of the received power at the point extracted atstep S23 is removed (S24), the coverage area map without an interferencearea is displayed (S25), and the process proceeds to step S10. As thecoverage area map without the interference area is displayed,interference of two radio waves can be reproduced, which is morepractical as compared to a case of simply displaying higher receivedpower.

When menu number M4 is selected at step S10, at step S21, received powerof a stronger radio wave of radio waves from the wireless transmittersat two access points AP1, AP2 is selected, the difference between thereceived power of two radio waves is calculated, a point with relativelylarge interference where the difference is less than or equal to thepredetermined threshold is extracted (S23), an interference area map isdisplayed (S26), and the process returns to step S10. As theinterference area map is displayed as described above, interference oftwo radio waves can be reproduced and an interference area can be simplydisplayed.

When menu number M5 is selected at step S10, at step S21, received powerof a stronger radio wave of radio waves from the wireless transmittersat two access points AP1, AP2 is selected, and at each point, thestrongest arrival direction is extracted from all directions (S31), thearrival direction map is displayed (S32), and the process returns tostep S10.

When menu number M6 is selected at step S10, at step S21, received powerof a stronger radio wave of radio waves from the wireless transmittersat two access points AP1, AP2 is selected, and at each point, thestrongest arrival surface direction is extracted from six surfaces, thatis, front, back, left, right, up, and down (S41), the arrival directionmap is displayed (S42), and the process returns to step S10.

With the radio-wave propagation simulation calculation display processdescribed above with reference to FIG. 6, a simulation calculation isperformed on six types of displays at steps S21, S22, S25, S26, S32, andS42 of FIG. 6 and these displays are displayed.

Next, an exemplary embodiment will be described hereinafter withreference to processes illustrated in FIGS. 7 and 8 performed by radiowave environment display device 100 illustrated in FIG. 1. The exemplaryembodiment describes representations of the following matters:

(1) How to move an access point in order to improve a radio waveenvironment

(2) Where to install a new access point in order to improve the radiowave environment

(3) Changes in the radio wave environment when an object such as aperson, which is an obstacle, moves

FIG. 7 is a flowchart of an access-point movement analysis processperformed by radio wave environment display device 100 illustrated inFIG. 1. Referring to FIG. 7, an analysis result obtained when a wirelesstransmitter at an access point is moved is displayed.

A user inputs first a movement range of an access point from apredetermined position to a destination point. The destination pointinput is defined as a terminal point.

Received power in an initial state is calculated at step S61 of FIG. 7,a result of the calculation is displayed (S62), and it is determinedwhether the access point has reached the terminal point input by theuser (S63). When the determination at step S63 is NO, the processproceeds to step S64. On the other hand, when the determination at stepS63 is YES, the process proceeds to step S67. While the calculationresult is displayed at step S62, the present disclosure is not limitedto this case and the calculation result need not to be displayed at thatstep.

A wireless transmitter is moved to a position of the access point thatis the terminal point at step S64, received power after movement iscalculated (S65), the calculation results of the received power in theinitial state and after movement are successively displayed (S66), andthe process returns to step S63. While the calculation result isdisplayed at step S66, the present disclosure is not limited to thiscase and the calculation result need not to be displayed at that step.

The calculation results of the received power in the initial state andafter movement are successively displayed at step S67 and the processends. When the calculation result is displayed in real time at step S66,the calculation result need not to be displayed at step S67.

As described above, the entire access-point movement analysis processillustrated in FIG. 7 is performed so as to fix the wireless transmitterat access point AP1 but move the wireless transmitter at access pointAP2, for example. Consequently, it is possible to visualize how to movean access point in order to improve a radio wave environment.

Alternatively, the entire access-point movement analysis processillustrated in FIG. 7 is performed so as to fix wireless transmitters attwo access points AP1, AP2 but move a wireless transmitter at anotheraccess point AP3, for example. Consequently, it is possible to visualizewhere to install a new access point.

FIG. 8 is a flowchart of a person movement analysis process performed byradio wave environment display device 100 illustrated in FIG. 1. While aperson is assumed to be a moving object in FIG. 8, various radio waveobstacles (vehicles) other than a person may be possible. A user inputsfirst a movement range of a person from one position to anotherposition. Points input are defined as a start point and a terminalpoint, respectively.

Received power when the person is at the start point is calculated atstep S81 of FIG. 8, a result of the calculation is displayed (S82), andit is determined whether the person has reached the terminal point(S83). When the determination at step S83 is NO, the process proceeds tostep S84. On the other hand, when the determination at step S83 is YES,the process proceeds to step S87. While the calculation result isdisplayed at step S82, the present disclosure is not limited to thiscase and the calculation result need not to be displayed at that step.

A position of the person is moved at step S84, received power aftermovement is calculated (S85), the calculation results of the receivedpower in the initial state and after movement are successively displayed(S86), and the process returns to step S83. While the calculation resultis displayed at step S86, the present disclosure is not limited to thiscase and the calculation result need not to be displayed at that step.

The calculation results of the received power in the initial state andafter movement are successively displayed at step S87 and the processends. When the calculation result is displayed in real time at step S86,the calculation result need not to be displayed at step S87.

As described above, it is possible to visualize a change in a radio waveenvironment in a received power distribution obtained when a personmoves within an area, for example.

(Modification)

FIG. 2 is a block diagram illustrating an example of a hardwareconfiguration of radio wave environment display device 100A andperipheral devices according to a modification. In the exemplaryembodiment, a received power distribution and the like are calculated ina simulation based on radio waves from wireless transmitters at accesspoints AP1, AP2 at steps S1 to S4 of the radio-wave propagationsimulation calculation display process illustrated in FIG. 6. Themodification of FIG. 2 includes three wireless transmitters T1 to T3,wireless receiver R1, and radio wave environment display device 100Athat controls these wireless transmitters and wireless receiver. Anactual experiment may be performed to receive radio waves from wirelesstransmitters T1 to T3 by wireless receiver R1 and perform the processesat steps S10 to S42 illustrated in FIG. 6. The access-point movementanalysis process illustrated in FIG. 7 and the person movement analysisprocess illustrated in FIG. 8 may also be performed in a similar manner.

While three wireless transmitters T1 to T3 are used in the modificationof FIG. 2, the present disclosure is not limited to this case. At leasttwo and four or more wireless transmitters may be installed at differentpositions and transmit different radio waves. That is to say, in a radiowave environment display device that displays a radio wave environmentin an area where a plurality of wireless transmitters located atdifferent positions transmit different radio waves, at a point in thearea, a highest intensity (maximum intensity) may be selected among aplurality of intensities that are magnitudes of received power of radiowaves from the wireless transmitters and displayed.

(Other Modifications)

In the exemplary embodiment and the modification described above, areceived power distribution in an area may be calculated and displayedwhen transmission of a radio wave from each of wireless transmitters attwo access points is ON or OFF.

Meshes that divide the area into points need not to have the same sizeand are uniform. That is to say, the meshes that divide the area intopoints may be set to have different sizes. For example, the size of amesh may be set to be larger than a predetermined value near a wirelesstransmitter at an access point because the intensity of radio waves issufficiently high. On the other hand, the size of the mesh may be set tobe smaller than the predetermined value at a point far away from thewireless transmitter at the access point because the intensity of radiowaves at this point is lower than the intensity of radio waves near thewireless transmitter at the access point.

While received power is calculated for each mesh that divides the areainto points, the present disclosure is not limited to this case. Forexample, the received power for a plurality of meshes may becollectively calculated and displayed, for example, an average of thereceived power may be calculated and displayed.

While the received power distribution is displayed in color, forexample, a change in received power over time may be displayed in a bargraph. In mobile communication system, reflected waves has to beconsidered because of a multi-pass environment. Consequently, “delayspread” as well as the received power distribution may be calculated anddisplayed.

The received power may be displayed in real time during a calculation ofthe received power. In particular, it is advantageous when the receivedpower is measured on the site, since a change in level is recognized inreal time when a surrounding object moves. In addition, an arrivaldirection can be displayed in real time by extracting a surface andpolarization of the maximum power. When a plurality of wirelessreceivers are installed and received power is calculated for display, aflow of radio waves at each point is visualized.

While the received power (dBm) is calculated in the exemplary embodimentand modifications described above, the present disclosure is not limitedto this case, and a received field intensity (V/m) of a radio wave maybe displayed.

In the exemplary embodiment and modifications described above, a radiowave environment display device that displays a radio wave environmentin an area where a plurality of wireless transmitters located atdifferent positions transmit different radio waves selects, at a pointin the area, a maximum intensity among intensities that are magnitudesof received power of radio waves transmitted from the wirelesstransmitters and causes a display unit to display the radio waveenvironment based on the highest intensity selected. In this case, themaximum intensity corresponds to the point in the area and is displayedas the radio wave environment.

The maximum intensity may be displayed while a point where a differencebetween two highest intensities among intensities that are magnitudes ofreceived power of radio waves transmitted from a plurality of wirelesstransmitters is less than or equal to a first threshold is removed frompoints in the area.

Alternatively, the maximum intensity may be displayed at a point where adifference between two highest intensities among intensities that aremagnitudes of received power of radio waves transmitted from thewireless transmitters is more than or equal to a second threshold, amongthe points in the area.

Among the points in the area, a point where a difference between twohighest intensities among intensities that are magnitudes of receivedpower of radio waves transmitted from the wireless transmitters is lessthan or equal to a third threshold may be selected and displayed.

For the points in the area, an arrival direction of a radio wave withthe highest intensity among intensities that are magnitudes of receivedpower of radio waves transmitted from the wireless transmitters isdisplayed. The arrival direction of the radio wave with the maximumreceived power is selected from six directions corresponding topredetermined six surfaces surrounding each point and displayed.

Radio wave environments before and after a change in a position of atleast one of the wireless transmitters are successively displayed.

Moreover, radio wave environments before and after movement of an objectin the area are successively displayed. Alternatively, a radio waveenvironment at a time when an additional wireless transmitter isinstalled at a position different from the positions of the wirelesstransmitters and radio wave environments before and after the additionalwireless transmitter is installed are successively displayed.

INDUSTRIAL APPLICABILITY

The present disclosure is capable of appropriately displaying a radiowave environment even if a plurality of wireless transmitters transmitdifferent radio waves and is, in particular, industrially useful forrecognizing the radio wave environment.

What is claimed is:
 1. A radio wave environment display device thatdisplays a radio wave environment in an area where a plurality ofwireless transmitters located at different positions transmit radiowaves, the radio wave environment display device comprising: a displayunit that displays the radio wave environment; and a controller thatselects, at each of a plurality of points in the area, a maximumintensity among intensities that are magnitudes of received power ofradio waves transmitted from the wireless transmitters, selects, at eachof the plurality of points in the area, a second highest intensity amongintensities that are magnitudes of received power of radio wavestransmitted from the wireless transmitters, and causes the display unitto display a remaining point removing a point where a difference betweenthe maximum intensity and the second highest intensity is less than orequal to a first threshold from the plurality of points as the radiowave environment.
 2. The radio wave environment display device accordingto claim 1, wherein the controller causes the display unit to display anarrival direction of the radio wave with the maximum intensity at theremaining point.
 3. The radio wave environment display device accordingto claim 2, wherein the controller selects the arrival direction fromsix directions corresponding to predetermined six surfaces surroundingthe remaining point.
 4. The radio wave environment display deviceaccording to claim 1, wherein the controller causes the display unit tosuccessively display the radio wave environments before and after achange in a position of at least one of the wireless transmitters. 5.The radio wave environment display device according to claim 1, whereinthe controller causes the display unit to successively display the radiowave environments before and after movement of an object in the area. 6.The radio wave environment display device according to claim 1, whereinwhen an additional wireless transmitter different from the wirelesstransmitters is installed, the controller causes the display unit tosuccessively display the radio wave environments before and after theadditional wireless transmitter is installed.
 7. The radio waveenvironment display device according to claim 1, wherein the radio waveenvironment is displayed on a map that illustrates the area.
 8. Theradio wave environment display device according to claim 1, wherein thecontroller causes the display unit to display the maximum intensitycorresponding to the remaining point at the remaining point.
 9. A radiowave environment display device that displays a radio wave environmentin an area where a plurality of wireless transmitters located atdifferent positions transmit radio waves, the radio wave environmentdisplay device comprising: a display unit that displays the radio waveenvironment; and a controller that selects, at each of a plurality ofpoints in the area, a maximum intensity among intensities that aremagnitudes of received power of radio waves transmitted from thewireless transmitters, selects, at each of the plurality of points inthe area, a second highest intensity among intensities that aremagnitudes of received power of radio waves transmitted from thewireless transmitters, and causes the display unit to display a pointwhere a difference between the maximum intensity and the second highestintensity is more than or equal to a second threshold among theplurality of points as the radio wave environment.
 10. The radio waveenvironment display device according to claim 9, wherein the radio waveenvironment is displayed on a map that illustrates the area.
 11. Theradio wave environment display device according to claim 9, wherein thecontroller causes the display unit to display the maximum intensitycorresponding to the point at the point.
 12. The radio wave environmentdisplay device according to claim 9, wherein the controller causes thedisplay unit to display an arrival direction of the radio wave with themaximum intensity at the point.
 13. The radio wave environment displaydevice according to claim 12, wherein the controller selects the arrivaldirection from six directions corresponding to predetermined sixsurfaces surrounding the point.
 14. The radio wave environment displaydevice according to claim 9, wherein the controller causes the displayunit to successively display the radio wave environments before andafter a change in a position of at least one of the wirelesstransmitters.
 15. The radio wave environment display device according toclaim 9, wherein the controller causes the display unit to successivelydisplay the radio wave environments before and after movement of anobject in the area.
 16. The radio wave environment display deviceaccording to claim 9, wherein when an additional wireless transmitterdifferent from the wireless transmitters is installed, the controllercauses the display unit to successively display the radio waveenvironments before and after the additional wireless transmitter isinstalled.
 17. A radio wave environment display device that displays aradio wave environment in an area where a plurality of wirelesstransmitters located at different positions transmit radio waves, theradio wave environment display device comprising: a display unit thatdisplays the radio wave environment; and a controller that selects, ateach of a plurality of points in the area, a maximum intensity amongintensities that are magnitudes of received power of radio wavestransmitted from the wireless transmitters, selects, at each of theplurality of points in the area, a second highest intensity amongintensities that are magnitudes of received power of radio wavestransmitted from the wireless transmitters, and causes the display unitto display a point where a difference between the maximum intensity andthe second highest intensity is less than or equal to a third thresholdamong the plurality of points as the radio wave environment.
 18. Theradio wave environment display device according to claim 17, wherein theradio wave environment is displayed on a map that illustrates the area.19. The radio wave environment display device according to claim 17,wherein the controller causes the display unit to display the maximumintensity at the point.
 20. The radio wave environment display deviceaccording to claim 17, wherein the controller causes the display unit todisplay an arrival direction of the radio wave with the maximumintensity at the point.
 21. The radio wave environment display deviceaccording to claim 20, wherein the controller selects the arrivaldirection from six directions corresponding to predetermined sixsurfaces surrounding the point.
 22. The radio wave environment displaydevice according to claim 17, wherein the controller causes the displayunit to successively display the radio wave environments before andafter a change in a position of at least one of the wirelesstransmitters.
 23. The radio wave environment display device according toclaim 17, wherein the controller causes the display unit to successivelydisplay the radio wave environments before and after movement of anobject in the area.
 24. The radio wave environment display deviceaccording to claim 17, wherein when an additional wireless transmitterdifferent from the wireless transmitters is installed, the controllercauses the display unit to successively display the radio waveenvironments before and after the additional wireless transmitter isinstalled.
 25. A method for displaying a radio wave environment that isperformed by a radio wave environment display device that displays aradio wave environment in an area where a plurality of wirelesstransmitters located at different positions transmit radio waves, themethod comprising: selecting, at each of a plurality of points in thearea, a maximum intensity among intensities that are magnitudes ofreceived power of radio waves transmitted from the wirelesstransmitters; selecting, at each of the plurality of points in the area,a second highest intensity among intensities that are magnitudes ofreceived power of radio waves transmitted from the wirelesstransmitters; and displaying a remaining point removing a point where adifference between the maximum intensity and the second highestintensity is less than or equal to a first threshold from the pluralityof points as the radio wave environment.
 26. A method for displaying aradio wave environment that is performed by a radio wave environmentdisplay device that displays a radio wave environment in an area where aplurality of wireless transmitters located at different positionstransmit radio waves, the method comprising: selecting, at each of aplurality of points in the area, a maximum intensity among intensitiesthat are magnitudes of received power of radio waves transmitted fromthe wireless transmitters; selecting, at each of the plurality of pointsin the area, a second highest intensity among intensities that aremagnitudes of received power of radio waves transmitted from thewireless transmitters, and displaying a point where a difference betweenthe maximum intensity and the second highest intensity is more than orequal to a second threshold among the plurality of points as the radiowave environment.
 27. A method for displaying a radio wave environmentthat is performed by a radio wave environment display device thatdisplays a radio wave environment in an area where a plurality ofwireless transmitters located at different positions transmit radiowaves, the method comprising: selecting, at each of a plurality ofpoints in the area, a maximum intensity among intensities that aremagnitudes of received power of radio waves transmitted from thewireless transmitters; selecting, at each of the plurality of points inthe area, a second highest intensity among intensities that aremagnitudes of received power of radio waves transmitted from thewireless transmitters; and displaying a point where a difference betweenthe maximum intensity and the second highest intensity is less than orequal to a third threshold among the plurality of points as the radiowave environment.